Tetrodotoxin is a potent neurotoxin found in certain fish and other aquatic animals, although it is actually produced in symbiotic bacteria hosted in these creatures.There is some ambiguity in the literature and on other databases as to the exact stereochemistry of tetrodotoxin. Our structure matches that on ChEBI and the PubChem entry linked to above, while the compound is also represented by the alternative isomer in CHEMBL507974 and CID 11174599.